1. Field of the Invention
The present invention relates to a heat exchanging type boiler, and more particularly, to a heat exchanging type boiler that produces heating gas of a bubble shape come into contact with water in a water reservoir, thus to make it possible to heat the water therein.
2. Description of the Related Art
Generally, a boiler is a device which heats water in a closed tank from the inside or outside in order to provide hot water or steam at high temperature and high pressure. The water or steam at the high temperature is used for the heating in a building, while it at the high pressure is used for the activation of a steam turbine in a heat power station to thereby produce electric power.
Various studies for the boiler are made to reduce an amount of waste heat energy except an amount of heat energy consumed for heating water. Recently, there is provided a supercharged boiler that is adapted to supply compressed air in a combustion chamber in order to improve a combustion efficiency in the combustion chamber.
Typically, the conventionally developed boiler is provided with a water retaining reservoir which is made of a metal material having a high heat conductivity and in which a predetermined amount of water is contained. In order to produce steam, thus, the water retaining reservoir is heated from the inside or outside, or a water pipe through which the water passes communicates to the combustion chamber such that the water pipe is heated.
In other words, the heating gas (which is generated by burning solid, liquid or gas) at the high temperature as a heat source in the conventionally used boiler comes in contact with the water retaining reservoir or the water pipe having the high heat conductivity such that heat energy is primarily transferred from the heating gas to the water retaining reservoir or the water pipe and the water retaining reservoir or the water pipe to which the heat energy is transferred comes in contact with water, thereby secondarily transferring the heat energy to the water. In this case, the conventional boiler heats the water in an indirect way of making the heat energy of the heat gas necessarily pass through the water retaining reservoir or the water pipe as a heat transfer medium on a path where the heat energy is transferred to the water.
In the conventionally used boiler, however, the heat energy, which passes through the water retaining reservoir or the water pipe, is much consumed for raising the temperature of the reservoir or the water pipe such that the heat energy is easily emitted to the outside of the boiler due to the high heat conductivity of the water retaining reservoir or the water pipe, which makes the heat efficiency of the boiler substantially low. In addition, the convection current of water in the water retaining reservoir or the water pipe is only used in order to raise the total temperature of the water, such that heating speed is very low and it is difficult to increase the heat efficiency over a predetermined level.
In order to expand the heat transfer area of the reservoir or the pipe, also, the reservoir or the pipe is designed to be bent many times, which results in a high manufacturing cost. Due to the complicated structure, moreover, a relatively long period of time is consumed to clean the reservoir or the pipe.
The water retaining reservoir or the water pipe has the high heat conductivity, but has a relatively low chemical resistance, such that it can be easily to be exposed to corrosion. And, the impurities in the water are combined to produce scale that is attached onto the inner wall of the water retaining reservoir, which makes the heat transfer efficiency substantially low. Thereby, the heat expansion on the wall surface of the water retaining reservoir occurs unevenly such that the boiler is broken. This results in the decrement of the life cycle of the boiler and frequent cleaning of the interior of the boiler.